Hi, I have an 8-month-old "puppy" who seems to be regressing in his housebreaking. My sister and I also have 4 cats in our apartment, and all animals are only allowed on the bottom floor of our unit. This is because we had serious damage in our previous apartment due to our cats preferring to pee on our carpets rather than in the 6+ litter boxes we provided them. We are now in a new apartment and we decided to fence off (baby gate) the upstairs, and leave the animals downstairs since it's hardwood. However, some of the stairs and the landing are still accessible to the animals (because of where the baby gate had to fit) and we found a couple of our cats starting to pee on those stairs. I always keep a puppy pad down for my dog and he was consistently using it, pooping and peeing on it during the time I was at work. Then probably starting a couple of months ago, I'd come back from work and notice several piles of poop on several different stairs, along with pee sometimes on the stairs (sometimes on the risers so I think he is marking?) and absolutely nothing on his pad. My sister and I ripped up the carpet on the landing that the cats kept peeing on and now they've stopped, but the carpet on the stairs is still there and this is where he's going-so it's weird to me that he's peeing there because I don't think the cats have ever gone there. But what's most puzzling to me is that I or my sister will take him out and then sometimes he will come right back inside and pee in a completely different area across the room near the back door on the hardwood! The cats don't pee there, but their litter boxes are near there, so maybe he thinks that's OK? I'm debating whether this is behavioral or some sort of bladder or other infection? Peeing on the hardwood after going outside is completely throwing me. If anyone has any ideas, please please share! Thank you!